Do you take a vitamin D supplement daily? Have you had your vitamin D levels tested? Most Canadians have heard the recommendation to take a vitamin D supplement but there are still many misconceptions. Read on to learn all about this important sunshine vitamin!

Role of Vitamin D

Vitamin D helps the body absorb calcium and is essential for promoting the growth of healthy bones and teeth. When we think about bone health and preventing osteoporosis, we often focus on calcium but vitamin D is a key factor too. Plus, vitamin D isn’t only important for bone health. It is actually a steroid hormone and required for many important functions in the body, including proper functioning of the immune system and the neurological system.

There is research connecting vitamin D deficiencies to an increased risk of certain conditions, including pre-eclampsia, multiple sclerosis, cardiovascular disease, certain autoimmune conditions, and certain cancers. However, there is further research needed to understand its role as a therapeutic treatment in the following situations:

• Treatment/prevention of asthma in children
• Decreasing the risk of pre-eclampsia, low birth weight, and preterm birth in pregnancy
• Improving insulin sensitivity in patient’s with type 1 and type 2 diabetes, as well as PCOS
• Treating symptoms of multiple sclerosis
• Reducing antibodies in autoimmune conditions, including autoimmune thyroid diseases

Vitamin D Testing

A blood test showing serum concentration of 25-hydroxy-vitamin-D (25(OH)D) is the preferred indicator for vitamin D status. This test will tell us whether you suffer from a vitamin D deficiency and, therefore, whether you need a higher dose of vitamin D to bring your levels back to normal. Unfortunately, OHIP doesn’t currently cover the cost of a vitamin D test so it isn’t routinely run by your doctor. However, there are conditions in which the testing can be covered, including if you suffer from osteopenia/osteoporosis, celiac disease, or other malabsorption diseases.

Sources of Vitamin D

We mainly get vitamin D from the sun. The UV rays help convert vitamin D precursors in the skin into the active form of vitamin D. However, anything that blocks UV rays can affect this reaction in the skin. Factors that affect UV rays include season, time of day, cloud cover, skin pigmentation, and sunscreen use. Unfortunately, we don’t have a precise answer for how much these factors affect vitamin D production and how much time must be spent exposed to the sun to get adequate amounts of vitamin D.

Food sources of vitamin D are limited but they are available. Vitamin D is naturally found in fatty fish and egg yolks. It is also commonly fortified in cow’s milk, plant-based milks, and orange juice.

Supplementation

The recommended dosage for supplementation is generally between 400 IU – 2000 IU daily but this depends on your age and risk factors. Vitamin D supplements come in two forms, D2 and D3, but vitamin D3 is the more common and preferred form. At the correct dose, it is safe and recommended for infants, children, and pregnant women. However, vitamin D is a fat soluble vitamin and, especially due to its effects on calcium, there is risk of toxicity at very high doses. It is best to talk to your healthcare practitioner about the best dose for you.

Supplementation is generally recommended for everyone but it is highly recommended in the following scenarios:

• Infants who are exclusively breastfed
• Adults over 50 years of age
• Individuals eating a vegan diet
• Individuals at high risk of osteoporosis
• Individuals with darkly pigmented skin (higher amounts of the melanin pigment decrease the skin’s ability to produce vitamin D from the sun’s UV rays)
• Individuals with malabsorption conditions, such as celiac disease and inflammatory bowel disease